stars like dust

Gorgeous Spitzer Space Telescope Image of Ω Centauri

Martha Boyer at the University of Minnesota got Spitzer images of Omega Cen, combines with ground based imaging from the Blanco 4m.

The goal was to find dust rich red giant stars, those are the red/yellow stars in the image, with the main sequence coloured blue.

Omega Centauri, classified as a globular cluster, has been known for some time to have multiple stellar generations, which is unusual for a globular. It also is suspected to have a central intemediate mass black hole, inferred from the rising central stellar velocity dispersion, which is a signature of a possible central black hole.
Omega Cen is also know to have a peculiarly low proportion of central blue straggler stars.

The simplest explanation for these anomalies, is that Omega Centauri is not really a proper globular cluster, but is rather the stripped central bulge of a dwarf galaxy.
In which case the cluster used to be the compact central region of a dwarf galaxy, maybe a hundred times more massive than the current remnant, and much bigger in spatial extent.

In the meantime, we get to ponder why red giants in Omega Cen are not making metal dust at the rate they ought to be.